It is known that isolated volumes of air may be trapped between the edges of a tire and the rim bed when tires are mounted on vehicle rims. Such vehicle wheels with these trapped air volumes are subsequently balanced. This may result in undesirable imbalance conditions after such trapped air volumes escape, in particular during subsequent driving around curves when loads are applied to the tires. This is undesirable especially after delivery of new vehicles and represents a deficiency of quality, even if a relatively rare one, and requires rebalancing in a workshop. Devices for elimination of such trapped air volumes have already been disclosed.
A generic device for optimizing bead seating (disclosed in DE 40 06 182 A1) consists of two lower and two upper contact pressure wheels which effect rotation of a wheel of a vehicle. At the same time, the vehicle wheel is held in its position by the four contact pressure wheels. The axis of rotation of the vehicle wheel is horizontal during the process. Side clamping disks which cause deformation of the tire sides are pressed against both sides of the vehicle tire for optimizing bead seating. Bead seating is accordingly optimized in that each of the edges of the tire comes in contact with the rim bed without trapped air volumes as it rotates.
The complete structure of the generic device comprises a lower part, an upper part, and a stay mounted between the upper and the lower part as a connecting element. The upper part may be displaced vertically in relation to the lower part. Two pressure application wheels are mounted on the top of the lower part and also on the bottom of the upper part. The diameter of the contact pressure wheels is very small in comparison to the diameter of the vehicle wheel. Pivoting movement of the contact pressure wheels is not provided. In addition, the vehicle wheel cannot be pivoted out of its axis of rotation. The upper part of the device may be displaced horizontally backward from an operating position to a non-operating position in order to create sufficient clearance for fitting the device with components or for removing the seating-optimized tire.
In order for a vehicle wheel to be optimized it must be positioned in the device on the two contact pressure wheels of the lower part with horizontal axis of rotation. The next operating step is moving the upper part from its non-operating position to its operating position. In order for the vehicle wheel to be immobilized in its optimization position, the upper part is displaced vertically in the direction of the lower part until the contact pressure wheels on the bottom of the upper part come into contact with the vehicle wheel introduced into the device and accordingly hold this wheel stationary. The contact pressure wheels of the lower part are operated and the vehicle wheel is set in rotary movement by means of a drive device in the lower part of the device. The two side clamping disks are now pressed by means of a hydraulic control unit against the sides of the tire of the vehicle wheel and the sides of the tire are correspondingly deformed. Normal driving around curves is thereby simulated and optimized bead seating thus ensured. In order for it to be possible to remove the vehicle wheel from the device, the upper part must be moved first vertically upward and then horizontally rearward into its non-operating position.
Consequently, the entire seating optimization process for a vehicle wheel, including fitting of the device with components and removal, takes so long that the generic device does not appear to be suitable at least for use by a vehicle manufacturer involving large numbers of individual vehicle wheels. As a result of the upright positioning of the vehicle wheel, one worker is always required who holds the vehicle wheel in position after the device has been fitted with components, since immobilization of the vehicle wheel in position is not ensured until after the upper part of the device has reached the operating position. Automation of the optimization process is not provided.
In another disclosed testing device (DE 37 23 767 C2) a vehicle wheel to be tested is pivotably mounted on an axis. This axis may be displaced vertically, so that the running surface of the vehicle wheel may be brought into contact with the running surface of the contact pressure wheel. The contact pressure wheel may be set in rotary movement by means of a drive mechanism. The axis of the vehicle wheel and the axis of the contact pressure wheel are mounted in parallel, without the possibility of adjustment. The orientation of the axes is horizontal. A costly measuring mechanism in the axis of the vehicle wheel permits measurement of the radial and axial forces applied to the vehicle wheel. The design and configuration of the device do not meet the requirements of the tire test stand for individual test tires. This device is not designed for bead seating optimization, especially on a large number of vehicle wheels.